There is a bimetal circuit breaker in the headlight switch instead of a fuse. In case of a short or a high current draw, the lights flash on and off instead of simply going out when a fuse blows. It's a safety factor to allow a driver to get stopped with a little bit of light instead of just flying blind. Almost all of the flashing light problems I've diagnosed and repaired since the early 1960's were caused by a short or a voltage leak to ground in the dimmer switch. It lives in a very hostile environment under the floorboard, where road dirt, rain, and salt try to destroy it, constantly. Halogen type headlights can also cause enough current flow to overload the circuit breaker in an original equipment headlight switch. Putting a set of relays in the headlight circuit and running only the relay energize current through the headlight switch and dimmer is the best long term solution to high current headlight problems.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!